The following process has been proposed as a process for producing a transparent laminate such as laminated glass, wherein a resin layer is interposed between a pair of transparent plates.
A process for producing a transparent laminate, which comprises:
(a) a step of forming a seal part along the edge of the surface of one transparent plate,
(b) a step of supplying a liquid curable resin composition for forming a resin layer to a region enclosed by the seal part,
(c) a step of laminating the other transparent plate on the curable resin composition for forming a resin layer in a reduced-pressure atmosphere to obtain a laminate having the curable resin composition for forming a resin layer hermetically sealed by the pair of the transparent plates and the seal part, and
(d) a step of curing the curable resin composition for forming a resin layer in such a state that the laminate is placed under the atmospheric pressure (Patent Documents 1 and 2).
And, the following methods are exemplified as the method for forming a seal part.
(1) A method of bonding a double sided adhesive tape along the edge of one transparent plate.
(2) A method of bonding a double sided adhesive tape along the edge of one transparent plate and applying a curable resin composition for forming a seal part on its upper surface.
(3) A method of applying a curable resin composition for forming a seal part, along the edge of one transparent plate.
(4) A method of applying a curable resin composition for forming a seal part having spacer particles mixed, along the edge of one transparent plate.
However, in the methods (1) and (2), it is necessary to cut the double sided adhesive tape at the time of bending the seal part at an angle of 90° at corners of the edge of the transparent plate, whereby a continuous seal part cannot be formed. Therefore, there will be a defect such that a curable resin composition for forming a resin layer leaks out from a space in the seal part.
Further, in the method (2), a plurality of steps are required for the formation of the seal part, such being cumbersome.
By the method (3), a seal part can easily be formed, but in order to bond the pair of transparent plates via the seal part without any space, it is necessary to cure the seal part after laminating the other transparent plate i.e. subsequent to the step (c). Therefore, during the step (b), it is likely that the curable resin composition for forming a seal part spreads in the width direction of the seal part and the shape of the uncured seal part deforms, whereby the height of the seal part cannot be sufficiently maintained. Therefore, it is difficult to make the curable resin composition for forming a resin layer to be supplied to the region enclosed by the seal part and the resin layer formed by curing it to be thick.
In the method (4), although it is possible to maintain the height of the seal part by the spacer particles, it is necessary to enlarge spacer particles when a thick resin layer is necessary, and if a curable resin composition for forming a seal part containing large spacer particles is applied by e.g. a dispenser, the dispensing portion is likely to be clogged with the spacer particles, and the application may not be smoothly carried out. Further, it is likely that the curable resin composition for forming a seal part flows out from the spacer to form spaces in the seal part, whereby a defect such as a leakage of the curable resin composition for forming a resin layer from the spaces in the seal part results.